Topic 4 of 5
Terminations, enclosures and IP codes
Most electrical faults happen at connections. A good termination is tight, has no bare conductor showing, and is inside a suitable enclosure.
Good terminations
- Strip only the sheath and insulation you need. Don't nick the conductor.
- No bare conductor showing outside the terminal, and no insulation trapped under the screw.
- Tighten to the maker's recommended torque, then tug-test.
- Sleeve bare CPCs green and yellow.
- Use crimped ferrules on fine stranded flexible conductors where needed, so strands don't splay.
- Terminations must be accessible for inspection, unless they're a maintenance-free type allowed to be hidden.
SWA glands
- A gland grips the armour and seals the cable into the enclosure.
- BW glands are for indoor, dry places. CW glands have an extra outer seal for outdoor or wet places.
- Fit a shroud over the gland for extra protection.
- An earth tag (banjo) under the gland's locknut connects the armour to the earthing system.
IP codes
The IP (ingress protection) code shows how well an enclosure keeps out solid objects and water. First digit: solids, from 0 to 6. Second digit: water, from 0 to 8. An X means that part isn't specified.
| Code | Means |
|---|---|
| IP2X | Protected against fingers (objects over 12.5 mm) |
| IP4X | Protected against objects over 1 mm, such as wires |
| IP5X / IP6X | Dust protected / dust-tight |
| IPX4 | Protected against splashing water from any direction |
| IPX5 / IPX6 | Protected against water jets / powerful jets |
| IPX7 | Temporary immersion |
BS 7671 requires enclosures to be at least IP2X or IPXXB, and IP4X or IPXXD on top surfaces that are easy to reach, where things can be dropped in.
Exam tip: in IP65, the 6 means dust-tight and the 5 means protected against water jets.
Mini test
6 questions. Pick an answer to see if you're right and why.